Muscle strength, postural balance, and cognition are associated with braking time during driving in older adults

Background: Despite the well-known declines in driving performance with advancing age, there is little understanding of the specific factors that predict changes in key determinants such as braking time. Objectives: The aims of this study were to determine the extent to which age, muscle strength, cognition and postural balance are associated with braking performance in middle-aged and older adults. Methods: Male and female middle-aged adults (n = 62, age = 39.3 +/- 7.1 years) and older adults (n = 102, age = 70.4 +/- 5.8 years) were evaluated for braking performance, as well as in several motor and cognitive performance tasks. The motor evaluation included isokinetic ankle plantar flexor muscle strength, handgrip strength, and postural balance with and without a cognitive task. The cognitive assessment included the Mini Mental State Examination. Braking performance was measured using a driving simulator. Results: Older adults exhibited 17% slower braking time, lower strength, and poorer performance in the postural balance (p < 0.001). For both older and middle-aged adults, significant correlates of braking time included performance in the postural balance tests, muscle strength, and cognitive function. However, after full model adjustment, only postural balance and cognitive function were significantly associated. Conclusion: Muscle strength, postural balance, and cognition are associated with braking time, and may affect the safety of and driving performance in older adults. These findings may help to inform specific targeted interventions that could preserve driving performance during aging. (C) 2016 Elsevier Inc. All rights reserved.